#include <iostream>
#include <cmath>
#define PI 3.14159
using namespace std;
class Circle {
private:
    double radius;

public:
    void setRadius(double r) {
        radius = r;
    }
    double getRadius(){
        return radius;
    }
    void area(){
        cout<<"area:"<<PI*radius*radius<<endl;
    }
    void perimeter(){
        cout<<"perimeter:"<<2*PI*radius<<endl;
    }
};
int main()
{
    Circle cir;
    cir.setRadius(5.0);
    cir.area();
    cir.perimeter();
    return 0;
}
